Australia: The Land Where Time Began

A biography of the Australian continent 

Abrupt Change in Atmospheric CO₂ During the Last Ice Age

Atmospheric carbon dioxide concentrations and temperature in Antarctica varied in a similar fashion on millennial time scales during the last glacial period, though it was indicated by previous work that these changes were gradual. Ahn et al. carried out detailed analysis of 1 event and their results show that approximately half of the increase of CO₂ concentration occurred during the 1,500 year cold period between Dansgaard-Oeschger (DO) 8 & 9 the increase occurred rapidly, over less than 200 years. They also found that the carbon dioxide increase was either synchronous with a rapid increase of the Antarctic temperature that is inferred from stable isotopes.

Important information about the variations in the past of atmospheric concentrations of CO₂ has been preserved in ancient ice cores in air trapped in the ice, which can be used to inform understanding of future climate change cycle feedbacks (Friedlingstein et al., 2006). It has been shown by previous work on ice cores for the last glacial period that CO₂ and temperature in Antarctica rose during long, cold stadial periods in the northern hemisphere, and the temperature in Antarctica cooled CO₂ rise slowed or stopped rising when stadials ended with abrupt warming in the northern hemisphere (e.g. Ahn & Brook, 2008; Bereitter et al., 2012). The governing mechanisms for the climate-carbon cycle interactions are not well understood, partly as a result of insufficient resolution, precision, and/or chronology of ice core records that have previously been published, though these observations have been simulated in models forced by freshwater input in the North Atlantic (Schmittner & Galbraith, 2008).

Sources & Further reading

1. Ahn, J., E. J. Brook, A. Schmittner and K. Kreutz (2012). "Abrupt change in atmospheric CO2 during the last ice age." Geophysical Research Letters 39(18): L18711.